About FCS

Familial Chylomicronaemia syndrome explained

Familial Chylomicronaemia Syndrome is an ultra-rare condition that affects 1 to 2 in a million of the population.

People with the condition have difficulty properly digesting certain fats because they lack or have limited amounts of the enzyme lipoprotein lipase or for some reason what they have doesn’t work..  This results in a massive accumulation of fatty droplets called chylomicrons in the circulation.  The presence of chylomicrons after fasting for 12-14 hours is associated with high levels of triglycerides.  Triglycerides are the biomarker for the condition, meaning that high triglycerides in the blood indicate there is a problem with fat metabolism and can alert professionals to FCS. Triglycerides are measured in a simple fasting blood test.

If too much fat is eaten it does not get cleared from the body and instead travels round in the blood creating its creamy appearance which is typical of the  condition.



The photo shows 1ml of blood from a young boy with FCS, His triglyceride levels are 116.7 mmol/L.  The creamy white appearance of the blood is the fat that his body has not ben able to remove. The normal range of triglycerides is below 2 mmol/L.

Advances in the understanding of our genetic make-up have led to the identification of a number of genes which can cause the lack of ability to digest fat (and it is anticipated that more will be found in the future).


Some of the genes that are known to cause Famial Chylomicronaemia Syndrome include those for familial lipoprotein lipase (LPL) deficiency, apolipoprotein C-II (APO C-II) deficiency or mutations that affect APOA5, GP1HBP1 and LMF1 genes.(1)(2)

The lipoprotein lipase gene is the most prevalent, present in around 80% of people with FCS.


Umbrella Slide (jill prawer)FCS is a recessive genetic disorder meaning that the patient has to inherit one faulty gene from both of his or her parents.  The parents could have FCS themselves or be ‘carriers’. Carriers have one faulty gene and one functional gene and mostly appear unaffected.  However, there is increasing evidence that can be effects in later life for some carriers.

FCS affects men and women equally (although its impact is arguably greater on women) and there seems to be no ethnic bias, however there are a greater proportion of patients in Quebec, Canada due to the ‘founder effect’  The founder effect is where early settlers to the area carried the faulty gene and due to marriage within the community increased the presence of the faulty gene.  Here in the UK there are clusters of patients from the South Asian community for the same reason.

Download our leaflet (below).  If you would like copies sent to you – useful to distribute to those who need help in understanding the condition – or if you are a medical professional, then please give us the address to send them to and how many you require.  Please send me some leaflets.